A torn ACL typically cannot be repaired because it cannot heal. Therefore it must be reconstructed. ACL reconstruction involves replacing of the ligament with a similarly sized piece of tissue, known as a graft. After healed in position, the graft is intended to function like a normal ACL.
A commonly performed technique for reconstructing the ACL is the “transtibial” technique. In this technique, a bone tunnel is drilled through the tibia such that the tunnel enters the knee joint where the ACL would normally attach. A drill guide is then inserted through the drilled tunnel to position a guide wire on the femur. A cannulated reamer is used to drill a second bone tunnel on the femur. A graft is then passed through the tibial tunnel, across the joint space and into the femoral tunnel. When the graft is fixed in position, it connects the two normal attachment points of the original ACL, thereby replicating the function of a normal ACL.
Recent medical studies suggest potential problems associated with the transtibial technique. The primary limitation of conventional devices is the tibial tunnel itself; because the tibial tunnel is a rigid cylinder, it limits mobility of conventional instrumentation, making it nearly impossible to reach the ideal position on the femur for attaching the graft.
An alternative to the transtibial technique is the AM portal technique. In this technique, a drill guide is passed through a small incision at the joint line, known as the anteromedial (AM) portal, rather than through the tibial tunnel. The drill guide directs the guide wire to an anatomic position on the femur. Conventional guides require that the guide wire be inserted through the AM portal incision together with the guide. To safely direct the guide wire, the knee must be hyper-flexed thus requiring additional staff in the operating room. Additionally, the AM portal technique is more difficult because the hyper-flexed knee decreases the surgeon's ability to see inside the joint space. Another problem with this technique is that it has been shown to direct the guide wire out of the knee in such a way that the trajectory of the guide wire results in a much less usable femoral tunnel. In other words, the insertion point of the wire may be anatomically correct, but the trajectory of the wire is frequently incorrect which may hinder the surgeon's ability to adequately fix the graft on the femoral side.
Many practicing orthopedic surgeons were trained to perform ACL reconstructions using the transtibial technique, however, most orthopedic surgeons perform a relatively small number of ACL reconstruction surgeries each year. As such, the use of an unfamiliar and more complicated technique is less desirable for many practitioners. Moreover, conventional transtibial instrumentation has—to date—not been able to accomplish anatomic graft positioning on the femur.
Therefore, what is needed is a new surgical system that will address the aforementioned problems. In particular, what is needed is a surgical system that allows orthopedic surgeons to perform ACL reconstructions utilizing the principles of the relatively easier transtibial technique, while providing the improved graft positioning associated with the more technically difficult AM portal technique.